This invention relates to a device for mounting a mould in a machine that makes sanitaryware.
In particular, but not exclusively, the device according to the invention may be used in machines that make sanitaryware by casting slip under pressure in porous moulds.
One of the most well-known types of machine, considered in this specification purely by way of example without limiting the scope of the solution provided by the invention, is a single mould type machine which basically comprises a mould divided into two half-moulds (“male” and “female”) which are joined to form an internal cavity where the article of sanitaryware is formed. Each of the half-moulds is mounted on a vertical support or platen.
The two platens face each other and can move relative to each other along a bed or on overhead rails along a substantially horizontal line, or clamping line. When the two platens are close together, the half-moulds are joined so that the slip can be cast under pressure in the mould cavity to make an article of sanitaryware such as (for example) a shower tray, washbasin, flush tank, washbasin pedestal, and so on.
Usually, each half-mould also comprises a service plate that can be placed between the platen and an active porous resin filtering portion of the half-mould.
This plate covers or protects service circuits such as the half-mould drainage system.
With its regular, rigid surface, the service plate also acts as mechanical positioning element between the active porous resin filtering portion of the mould (made of porous resin and hence elastic) and the surface of the platen. Acting between the service plate and the platen there are clamping means which securely fasten each half-mould to the respective platen.
Another part that might be found on the mould is the containment unit, that is, a device for opposing the forces generated transversally (i.e. radial forces) relative to the clamping line during pressure casting.
At present, one of the major drawbacks of machines of this kind (but also of multi-mould machines) is the excessive down time necessary for changing the mould, which obviously reflects negatively on the productivity of the machine.
As a general rule, the changeover procedure involves removing the mould, which also means disconnecting all the service circuits for the mould (water drainage, air, vacuum and pressure release to the atmosphere) and for making the sanitaryware (feed and discharge of slip and drainage air) and then mounting another mould and connecting up all the service circuits again.
For mounting the service plate to the platen, two or more clamps are used. The clamps are positioned against the service plate and then fastened to the platen.
This procedure, as may be well imagined, is extremely long and laborious not only because of the size and weight of the mould but also on account of the multiplicity of parts to be handled (such as the service circuits).
To reduce machine down time, the same Applicant as this invention has designed and constructed a machine (see patent EP 1.403.022) where one of the two platens can be tilted about its axis, substantially horizontal and perpendicular to the clamping line, to facilitate access to and substitution of the mould.
Using a forklift truck or crane, the whole mould is placed on the platen positioned horizontally and the abutting service plate is secured using the clamps. Next, the platen is tilted back to the vertical position to enable the two platens to be moved closer together so that the service plate can be fastened to the platen that is still free. The service circuits can then be connected up and the machine made ready to operate.
This tilting platen solution has undoubtedly improved mould accessibility, making the mould changing procedure easier and reducing machine down time. It is not, however, always available in single-mould machines and, above all, it is a solution that cannot be “transferred” to multi-mould machines.
In addition to that, it should be remembered that mould positioning in all machines, including those with tilting platen, is performed without a constant plate-platen reference (adaptation to assist fastening is done with the aid of the clamps) and adapting also the service connections: once again, that means excessively long mould changeover times.